Artificial cold wave-induced cerebral infarction in rats with carotid atherosclerosis

To investigate the effects of cold on blood pressure, serum endothelin-1 content, serum nitric oxide content, and morbidity of cerebral infarction, as well as assess the therapeutic effect of nimodipine. A total of 200 rats were initially assigned to a normal group (n = 10), sham group (n = 10), and carotid atherosclerosis group (n = 180), and subsequently the animals in the carotid atherosclerosis group were randomly assigned to three groups: non-cold (n = 59), cold treatment (n = 58), and nimodipine (n = 58). Rats in the cold and nimodipine groups experienced an artificial cold wave. The temperature was set at 22°C for 12 h (7:00 am to 7:00 pm) and then at 4°C for another 12 h (7:00 pm to 7:00 am), representing a cycle. The animals underwent three cycles of cold. Rats in the nimodipine group were treated with nimodipine and those in the cold group with given an equal volume of intragastric normal saline for 3 days. Hematoxylin and eosin staining showed features of carotid atherosclerosis in all animals. Blood pressure fluctuated with alteration of temperature. A temperature decrease was accompanied by an increase of blood pressure and elevation of serum levels of endothelium-1 and nitric oxide. In addition, although nimodipine could prevent the cold-induced increase of blood pressure and elevation of serum endothelium-1 and nitric oxide levels, it had no effect on blood pressure fluctuation or morbidity of cerebral infarction. The results suggest that dramatic variation in temperature is one of the main causes of cold-induced fluctuation of blood pressure.